Tailpipe Emissions ‘Will Become Irrelevant Metric’

by | Jul 15, 2013

LowCVP-Emissions-scenarios-jul12Increased use of plug-in electric vehicles will allocate more of the total carbon emissions from cars and other vehicles to power stations and the production and disposal of vehicles and fuels, according to a study. As a result, future CO2e metrics for passenger cars need to take into account whole life-cycle CO2 emissions to measure environmental impacts, researchers from the Low Carbon Vehicle Partnership say.

This despite the fact that currently about 80 percent of greenhouse gas emissions occur during the in-use phase of a vehicle’s life, according to LowCVP.

The report suggests that the use of tailpipe CO2 emissions as an established comparator for different vehicles will become less effective, and almost irrelevant in terms of identifying the true carbon profiles and reduction potential for future vehicles.

For example, manufacturers are already beginning to focus on vehicle component materials and production processes. The materials used in production impact vehicles’ carbon footprint. As well, the use of lightweight steel and aluminum also affects emissions during the operation phase.

Life Cycle CO2e Assessment of Low Carbon Cars 2020-2030, prepared with PE International, shows how total life cycle CO2e emissions will change for different vehicle technologies.

The report also suggests that with ambitious policies, reductions in excess of 60 percent in lifetime CO2e impacts can be achieved by 2030 through a combination of factors from the production phase, use phases and end-of-life phase.

For example, recycling/re-use of high-impact vehicle components such as electric vehicle battery packs should contribute significantly to decarbonization efforts of the embodied impacts of future vehicles. Additional potential to deliver significant carbon reductions comes from factoring increased electrical mobility with battery vehicles and plug-in hybrids as well as low carbon liquid and gaseous fuels, LowCVP says.

According to the report, for “Typical case 2020” scenarios, there is a 5 percent to 12 percent range of savings in life-cycle CO2e impacts for all vehicles compared to the “Base 2012” scenarios. These savings mainly result from the expected reductions in the carbon intensity of the future grid mixes, fuel/electricity consumption savings from light-weighting and improved automotive technology as well as improvements in battery pack technology that are predicted to lead to lower embodied carbon impacts of this component.

LowCVP also developed a “Best case 2020” scenario in which the savings range from 9 percent to 24 percent for all vehicles compared to the “Base 2012” scenarios. Even further light-weighting and reductions in the carbon intensity of the future grid mixes are coupled with the use of 100 percent bioethanol in vehicles with internal combustion engines and a low-carbon intensity electricity grid mix. This leads to a 55 percent to 70 percent range of savings in total life-time CO2e impacts for all vehicles when compared to the “Base 2012” scenarios.

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